NORTHAMPTON – A legal substance that produces a high similar to that of smoking pot may not be illicit, but a growing number of western Massachusetts police departments are cracking down on stores that sell so-called synthetic marijuana — a substance that many communities across the country are seeking to ban.

Last month, Westfield police raided two convenience stores and seized an estimated $12,000 worth of synthetic pot and related drug paraphernalia. This week, Northampton police visited a few dozen city stores to educate and warn shopkeepers about the substance before further enforcement action is taken.

Republican file photoSynthetic marijuana is sold under many different names, including the popular K3 label.

Even though the phony pot is legal, Westfield police managed to criminally charge shop owners under a state law prohibiting the sale of substances that, when inhaled, alter one's state of mind. Massachusetts General Laws Chapter 270, Section 18, forbids the intentional inhalation of "fumes of any substance having the property of releasing toxic vapors, for the purpose of causing a condition of intoxication, euphoria, excitement, exhilaration, stupefaction, or dulled senses or nervous system, nor possess, buy or sell any such substance for the purpose of violating or aiding another to violate this section."

In November 2010, the U.S. Drug Enforcement Administration used its emergency powers capability to declare illegal several of the chemicals used to manufacture synthetic marijuana as lawmakers decide whether to ban the legal products. A federal bill to permanently ban the use of such chemicals and substances is currently wending its way through Congress. The House passed the measure on Dec. 8, 2011, and the bill is now before the Senate, which read the proposed legislation and sent it to the Committee on the Judiciary for review.

For now, though, some area police departments are pushing stores not to carry synthetic pot, sold under such labels as K2, K3, Blaze, Cloud 9, Posh, Red X Dawn, Spice and other product names.

Westfield's Board of Health is drafting municipal legislation that, if approved, would ban the sale of such substances within city limits. Now, the city of Northampton is the latest local municipality to set its sights on synthetic weed, which has been blamed for at least one death and numerous emergency-room cases.

"It's obviously a public safety issue for us," Northampton Police Detective Lt. Ken Watson told a CBS3 reporter, who accompanied Watson and Detective Sgt. Anne McMahon during a sweep of city stores this week.

"We're going to try and get this early on," Watson told the TV station, as he and McMahon passed out letters warning shopkeepers about the harmful effects of synthetic pot.

The cautionary notices were intended to get store owners to voluntarily remove the products before police take possible further action.

"We'll give it a few weeks and do some follow up to see if they are still selling it, and then we'll take enforcement actions at that time," Watson said.

Back in Westfield, Dr. Stanley D. Strzempko, vice president of medical affairs at Noble Hospital, called the use of synthetic drugs an "emerging issue" for health-care providers.

"This is one of those things that pops up on everyone’s radar screen at the same time, and we are just beginning to recognize what is happening," he told The Republican last month.

Strzempko characterized synthetic weed as "much worse than marijuana, with side effects that are much more severe."

Since about July, the doctor estimates he's treated about a half-dozen patients, including the case of a local teenager who smoked a blend called Cloud 9.

"I didn’t know at the time it was synthetic cannabinoids," the doctor said. "The patient was very anxious, had high blood pressure and high pulse rate, similar to the effects of cocaine."

Strzempko said the effect of the substance on the patient was "quite the opposite from the effects of smoking marijuana."

Synthetic marijuana resembles real marijuana. Product packaging typically identifies the contents as aromatic herbs, which are burned and inhaled through pipes or other paraphernalia commonly used for smoking pot and other drugs.

Chicopee Police Chief John R. Ferraro Jr. said his department is keeping a "close eye" on the situation. "We are aware of this product, and our drug unit is monitoring the situation," he said last month.

About one in nine high school seniors have gotten high in the past year on synthetic drugs, according to "Monitoring the Future," a comprehensive national survey of teenage drug use.

Material from CBS3, The New York Daily News, The New York Times, The Republican and USA Today was used in this report.